Crash in AnnotatingParser::parseTableGenValue

[jayfoad]

With clang-format built from current llvm-project sources (aff1242) I get:

$ clang-format clang/include/clang/Driver/Options.td
clang-format: clang/lib/Format/TokenAnnotator.cpp:316: bool clang::format::(anonymous namespace)::AnnotatingParser::parseParens(bool): Assertion `OpeningParen.is(tok::l_paren)' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.

[llvmbot]

@llvm/issue-subscribers-clang-format

Author: Jay Foad (jayfoad)

With `clang-format` built from current llvm-project sources (aff1242) I get: ``` $ clang-format clang/include/clang/Driver/Options.td clang-format: clang/lib/Format/TokenAnnotator.cpp:316: bool clang::format::(anonymous namespace)::AnnotatingParser::parseParens(bool): Assertion `OpeningParen.is(tok::l_paren)' failed. PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace. ```